POSIX threads are a set of functions that support applications with
requirements for multiple flows of control, called
threads
within a process.
Multithreading is used to improve the performance of a
program.
The POSIX thread functions are summarized in this section in the following
groups:
Thread Routines
Attribute Object Routines
Mutex Routines
Condition Variable Routines
Read/Write Lock Routines
Per-Thread Context Routines
Cleanup Routines
Thread Routines
int
Fo pthread_create
Fa pthread_t *thread const pthread_attr_t *attr
Fa void *lp]*start_routinerp]lp]void *rp] void *arg
Fc
Creates a new thread of execution.
int
pthread_cancel (pthread_t thread);
Cancels execution of a thread.
int
pthread_detach (pthread_t thread);
Marks a thread for deletion.
int
pthread_equal (pthread_t t1 pthread_t t2);
Compares two thread IDs.
void
pthread_exit (void *value_ptr);
Terminates the calling thread.
int
pthread_join (pthread_t thread void **value_ptr);
Causes the calling thread to wait for the termination of the specified thread.
int
pthread_kill (pthread_t thread int sig);
Delivers a signal to a specified thread.
int
pthread_once (pthread_once_t *once_control void lp]*init_routinerp]lp]voidrp]);
Calls an initialization routine once.
pthread_t
pthread_self (void);
Returns the thread ID of the calling thread.
int
pthread_setcancelstate (int state int *oldstate);
Sets the current thread's cancelability state.
int
pthread_setcanceltype (int type int *oldtype);
Sets the current thread's cancelability type.
void
pthread_testcancel (void);
Creates a cancellation point in the calling thread.
void
pthread_yield (void);
Allows the scheduler to run another thread instead of the current one.
Attribute Object Routines
int
pthread_attr_destroy (pthread_attr_t *attr);
Destroy a thread attributes object.
int
Fo pthread_attr_getinheritsched
Fa const pthread_attr_t *attr int *inheritsched
Fc
Get the inherit scheduling attribute from a thread attributes object.
int
Fo pthread_attr_getschedparam
Fa const pthread_attr_t *attr struct sched_param *param
Fc
Get the scheduling parameter attribute from a thread attributes object.
int
pthread_attr_getschedpolicy (const pthread_attr_t *attr int *policy);
Get the scheduling policy attribute from a thread attributes object.
int
pthread_attr_getscope (const pthread_attr_t *attr int *contentionscope);
Get the contention scope attribute from a thread attributes object.
int
pthread_attr_getstacksize (const pthread_attr_t *attr size_t *stacksize);
Get the stack size attribute from a thread attributes object.
int
pthread_attr_getstackaddr (const pthread_attr_t *attr void **stackaddr);
Get the stack address attribute from a thread attributes object.
int
pthread_attr_getdetachstate (const pthread_attr_t *attr int *detachstate);
Get the detach state attribute from a thread attributes object.
int
pthread_attr_init (pthread_attr_t *attr);
Initialize a thread attributes object with default values.
int
pthread_attr_setinheritsched (pthread_attr_t *attr int inheritsched);
Set the inherit scheduling attribute in a thread attributes object.
int
Fo pthread_attr_setschedparam
Fa pthread_attr_t *attr const struct sched_param *param
Fc
Set the scheduling parameter attribute in a thread attributes object.
int
pthread_attr_setschedpolicy (pthread_attr_t *attr int policy);
Set the scheduling policy attribute in a thread attributes object.
int
pthread_attr_setscope (pthread_attr_t *attr int contentionscope);
Set the contention scope attribute in a thread attributes object.
int
pthread_attr_setstacksize (pthread_attr_t *attr size_t stacksize);
Set the stack size attribute in a thread attributes object.
int
pthread_attr_setstackaddr (pthread_attr_t *attr void *stackaddr);
Set the stack address attribute in a thread attributes object.
int
pthread_attr_setdetachstate (pthread_attr_t *attr int detachstate);
Set the detach state in a thread attributes object.
Mutex Routines
int
pthread_mutexattr_destroy (pthread_mutexattr_t *attr);
Destroy a mutex attributes object.
int
pthread_mutexattr_getprioceiling (pthread_mutexattr_t *attr int *ceiling);
Obtain priority ceiling attribute of mutex attribute object.
int
pthread_mutexattr_getprotocol (pthread_mutexattr_t *attr int *protocol);
Obtain protocol attribute of mutex attribute object.
int
pthread_mutexattr_gettype (pthread_mutexattr_t *attr int *type);
Obtain the mutex type attribute in the specified mutex attributes object.
int
pthread_mutexattr_init (pthread_mutexattr_t *attr);
Initialize a mutex attributes object with default values.
int
pthread_mutexattr_setprioceiling (pthread_mutexattr_t *attr int ceiling);
Set priority ceiling attribute of mutex attribute object.
int
pthread_mutexattr_setprotocol (pthread_mutexattr_t *attr int protocol);
Set protocol attribute of mutex attribute object.
int
pthread_mutexattr_settype (pthread_mutexattr_t *attr int type);
Set the mutex type attribute that is used when a mutex is created.
int
pthread_mutex_destroy (pthread_mutex_t *mutex);
Destroy a mutex.
int
Fo pthread_mutex_init
Fa pthread_mutex_t *mutex const pthread_mutexattr_t *attr
Fc
Initialize a mutex with specified attributes.
int
pthread_mutex_lock (pthread_mutex_t *mutex);
Lock a mutex and block until it becomes available.
int
Fo pthread_mutex_timedlock
Fa pthread_mutex_t *mutex const struct timespec *abstime
Fc
Lock a mutex and block until it becomes available or until the timeout expires.
int
pthread_mutex_trylock (pthread_mutex_t *mutex);
Try to lock a mutex, but do not block if the mutex is locked by another thread,
including the current thread.
int
pthread_mutex_unlock (pthread_mutex_t *mutex);
Unlock a mutex.
Condition Variable Routines
int
pthread_condattr_destroy (pthread_condattr_t *attr);
Destroy a condition variable attributes object.
int
pthread_condattr_init (pthread_condattr_t *attr);
Initialize a condition variable attributes object with default values.
int
pthread_cond_broadcast (pthread_cond_t *cond);
Unblock all threads currently blocked on the specified condition variable.
int
pthread_cond_destroy (pthread_cond_t *cond);
Destroy a condition variable.
int
pthread_cond_init (pthread_cond_t *cond const pthread_condattr_t *attr);
Initialize a condition variable with specified attributes.
int
pthread_cond_signal (pthread_cond_t *cond);
Unblock at least one of the threads blocked on the specified condition variable.
int
Fo pthread_cond_timedwait
Fa pthread_cond_t *cond pthread_mutex_t *mutex
Fa const struct timespec *abstime
Fc
Wait no longer than the specified time for a condition
and lock the specified mutex.
int
pthread_cond_wait (pthread_cond_t * pthread_mutex_t *mutex);
Wait for a condition and lock the specified mutex.
Read/Write Lock Routines
int
pthread_rwlock_destroy (pthread_rwlock_t *lock);
Destroy a read/write lock object.
int
Fo pthread_rwlock_init
Fa pthread_rwlock_t *lock const pthread_rwlockattr_t *attr
Fc
Initialize a read/write lock object.
int
pthread_rwlock_rdlock (pthread_rwlock_t *lock);
Lock a read/write lock for reading, blocking until the lock can be
acquired.
int
pthread_rwlock_tryrdlock (pthread_rwlock_t *lock);
Attempt to lock a read/write lock for reading, without blocking if the
lock is unavailable.
int
pthread_rwlock_trywrlock (pthread_rwlock_t *lock);
Attempt to lock a read/write lock for writing, without blocking if the
lock is unavailable.
int
pthread_rwlock_unlock (pthread_rwlock_t *lock);
Unlock a read/write lock.
int
pthread_rwlock_wrlock (pthread_rwlock_t *lock);
Lock a read/write lock for writing, blocking until the lock can be
acquired.
int
pthread_rwlockattr_destroy (pthread_rwlockattr_t *attr);
Destroy a read/write lock attribute object.
int
Fo pthread_rwlockattr_getpshared
Fa const pthread_rwlockattr_t *attr int *pshared
Fc
Retrieve the process shared setting for the read/write lock attribute
object.
int
pthread_rwlockattr_init (pthread_rwlockattr_t *attr);
Initialize a read/write lock attribute object.
int
pthread_rwlockattr_setpshared (pthread_rwlockattr_t *attr int pshared);
Set the process shared setting for the read/write lock attribute object.
Per-Thread Context Routines
int
pthread_key_create (pthread_key_t *key void lp]*routinerp]lp]void *rp]);
Create a thread-specific data key.
int
pthread_key_delete (pthread_key_t key);
Delete a thread-specific data key.
void *
pthread_getspecific (pthread_key_t key);
Get the thread-specific value for the specified key.
int
pthread_setspecific (pthread_key_t key const void *value_ptr);
Set the thread-specific value for the specified key.
Cleanup Routines
int
Fo pthread_atfork
Fa void lp]*preparerp]lp]voidrp]
Fa void lp]*parentrp]lp]voidrp]
Fa void lp]*childrp]lp]voidrp]
Fc
Register fork handlers
void
pthread_cleanup_pop (int execute);
Remove the routine at the top of the calling thread's cancellation cleanup
stack and optionally invoke it.
Push the specified cancellation cleanup handler onto the calling thread's
cancellation stack.
IMPLEMENTATION NOTES
The current
Fx POSIX thread implementation is built in two libraries,
Lb libthr ,
and
Lb libkse .
They contain both thread-safe versions of
Lb libc
functions and the thread functions.
Threaded applications are linked with one of these libraries.
